Figure 4. Gibbs free-energy of protein denaturation (G-G0, left) and derivative (∂G/∂ξ)T,p, (right) as a function of the degree of advancement ξ at the denaturation temperature Td (middle), below (upper) and above (lower) Td according to eqs. (5) and (6), respectively. The calculation refers to the α-Chymotrypsinogen A denaturation with Td = (273+55) K, Tbelow = (Td – 2) K, Tupper = (Td + 2) K and with the equilibrium constant values determined according to the Results Section. For the sake of simplicity n0 has been taken equal to 1 mol. The equilibrium state is specified by the (G-G0) minimum on the left and by the zero value of the (∂G/∂ξ)T,p derivative (the horizontal dashed lines) on the right. The equilibrium composition of the D form is indicated in correspondence on the two abscissa scales


Thermal Denaturation of Proteins and Chemical Equilibrium

Laura Moroni, Cristina Gellini, Pier Remigio Salvi

World Journal of Chemical Education. 2015, 3(3), 59-63 doi:10.12691/wjce-3-3-1